Posts tagged with Coleman & Temple

Below is a slightly reformatted version of the comments I submitted in response to the Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan/Draft Environmental Assessment. A PDF version is available here.

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To Whom It May Concern:

I am writing to comment on the Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan/Draft Environmental Assessment. As I point out below, the IPMP/EA proposed by FWS fails to adequately address—or overlooks entirely—several key issues. Only now, for example—after years of struggling with this issue—does FWS propose to “imple­ment monitoring and conduct further research as needed to determine abundance and distribu­tion of free-roaming cats throughout the Refuge, document effectiveness of management actions taken or not taken on cat populations, and determine the impacts on the ecosystems and native species to aid in the adaptive management process.” [1]

How can FWS even put forward its IPMP/EA without this critical information in hand? One would expect, under the circumstances, that population estimates and scat analysis, for in­stance—along with whatever additional research might better inform any proposed action by FWS—would form the basis of such an IPMP/EA.

In addition, the IPMP/EA fails to address risks inherent with the improper management of free-roaming cats in the Keys. The plan proposed by FWS is unlikely to result in the removal of cats at a rate sufficient to keep pace with reproduction—a situation exacerbated greatly by its insistence on banning the feeding of feral cats and Trap-Neuter-Return (TNR) programs. Consequently, the population of feral cats may very well increase. And even if FWS is successful at removing cats from some locations, the IPMP/EA fails to take into account the risk of meso­predator release—the inevitable spike in non-native rodent populations—and its impact on the native species the IPMP/EA aims to protect.

For these reasons (each of which is outlined in detail below), I strongly encourage FWS to revise its IPMP/EA, especially as it pertains to the removal of feral cats.

Justification for Action
After a thorough reading of the Draft Environmental Assessment (EA) for the Florida Keys Na­tional Wildlife Refuges Complex (FKNWRC) Integrated Predator Management Plan—along with several supporting documents (as described below)—I am struck by how inadequately the IPMP/EA addresses several critical issues. Indeed, the Plan’s Justification for Management Action suggests that FWS has an insufficient and/or largely incorrect understanding of the impacts of feral and free-roaming cats on native wildlife and the environment.

ExtinctionsAmong the studies FWS cites to support its claim that “free-roaming cats have been shown to be a major cause of 33 native species extinction globally,” [1] is a 1987 paper by Cruz and Cruz, in which the authors, studying Galápagos Petrels, found that cats were hardly the only culprits:

“They are threatened by introduced rats, which attack eggs and young chicks… dogs and pigs which prey on eggs, nestlings and adults. Introduced goats, burros and cattle destroy nesting habitat and trample nests. A different combination of these pests and predators exists at each of the petrel nesting sites, while three of the islands are plagued by all of them.” [2]

The FWS would have the public believe the Galápagos Petrel is among those 33 extinctions. In fact, the birds are still there, though they are listed as Critically Endangered.

The story is similar for the 1986 paper by Kirkpatrick and Rauzon, another purported link between free-roaming cats and species extinctions. In fact, Kirkpatrick and Rauzon found that more than 90 percent of the diet of free-roaming cats on Jarvis Island and Howland Island was made up of Sooty Terns, Wedge-tailed Shearwaters, and Brown Noddies—each of which is listed as a species of Least Concern. [3]

Another of the papers cited by FWS has nothing to do with extinctions at all. As the authors describe it, their study was an evaluation of “whether a collar-worn pounce protector, the CatBib, reduces the number of vertebrates caught by pet cats and whether its effectiveness was influenced by colour or adding a bell.” [4]

Also listed among the “evidence” of island extinctions were studies that—in addition to having nothing to do with extinctions—were not conducted on islands. Coleman and Temple’s 1993 sur­vey, for example, involved rural Wisconsin residents and their outdoor cats, [5] while Churcher and Lawton surveyed residents of a small English village. [6]

Threatened or Endangered Species
FWS’s assertion that “many of the species impacted by free-roaming cats are federally listed threatened or endangered species and federally protected migratory birds” [1] is, while probably true, also largely meaningless. According to the 2009 State of the Birds report, published by the De­partment of the Interior:

“The United States is home to a tremendous diversity of native birds, with more than 800 species inhabiting terrestrial, coastal, and ocean habitats, including Hawaii. Among these species, 67 are federally listed as endangered or threatened. An additional 184 are species of conservation concern because of their small distribution, high threats, or declining popula­tions.” [7]

That translates to approximately 31 percent of all birds in this country being species of concern. FWS makes it sound as if perhaps the cats are targeting these birds; in fact, it’s obvious that all forms of mortality pose an acute threat to these vulnerable populations.

Disruptions to Native Ecosystems
When it comes to the disruption caused by cats to “the abundance, diversity, and integrity of na­tive ecosystems,” FWS turns to, among others, studies by Hawkins [8] and Jessup. [9]

But Hawkins’ dissertation work is plagued with problems that raise serious doubts about his rather triumphant conclusions—“the preference of ground feeding birds for the no-cat treatment was striking,” [8] for example. A closer look reveals that five of the nine ground-feeding birds in his study showed no preference for either area of the study site (a fact Hawkins downplays con­siderably). Without any explanation for why these vulnerable bird species were indifferent to the presence of an opportunistic predator, Hawkins is in no position to make the causal connections he does.

Jessup cites some well-known predation studies, but his concern is not the (presumed) impact on wildlife, per se, but rather the wholesale condemnation of “trap, neuter, and reabandon,” [9] as he calls it.

Birds and Cats
FWS claims that “free-roaming cats kill at least one billion birds every year in the U.S., repre­senting one of the largest single sources of human-influenced mortality for small native wildlife,” [1] supporting the assertion with just three sources, one of which is Rich Stallcup’s 1991 article from the Observer, a publication of the Point Reyes Bird Observatory. But “A Reversible Catastrophe” is very light on science—and, frankly, Stallcup gets most of that wrong. Mainly, the article is Stallcup’s manifesto regarding neighborhood cats:

“If you have a garden, why not proclaim it a wildlife sanctuary and protect it from non-native predators? If roaming cats come into your sanctuary to poach the wildlife under your steward­ship, you have the right and perhaps even the duty to discourage them in a serious way.” [10]

Stallcup goes on to suggest that gardeners “…try a B-B or pellet gun. There is no need to kill or shoot toward the head, but a good sting on the rump seems memorable for most felines, and they seldom return for a third experience.” [10]

Another of the studies cited by FWS—a 2008 paper by Sax and Gaines—isn’t about cats at all. Or even invasive animals. Although the authors do mention “the extinction of many native animal species on islands” [11] briefly in their introduction, the purpose of the paper is, as the authors state plainly enough, to “show that the number of naturalized plant species has increased linearly over time on many individual islands.” [11, emphasis mine]

Nevertheless, the assertion—made by FWS and many others, too—that “cats kill at least one billion birds every year in the U.S.” deserves careful scrutiny. Such aggregate figures can typically be traced to small—often flawed—studies, the results of which are subsequently extrapolated from one habitat to another, conflating island populations with those on continents, combining common and rare bird species, and so forth. Perhaps the most famous example of such pseudosci­entific manipulation is the infamous “Wisconsin Study” by Coleman and Temple.

Actually, there was no Wisconsin Study, in the scientific, peer-reviewed-publication sense. The often-cited “estimates”—which have, over the past 15 years, taken on mythical status—were nothing more than back-of-the envelopes guesses. Indeed, co-author Stanley Temple himself admitted that their figures weren’t “actual data,” though many—including the FWS—continue treating these figures as if they were actual data. “That was just our projection to show how bad it might be,” noted Temple. [12]

But Temple wasn’t as forthright about was the origin of their “estimates.” The authors’ “inter­mediate” figure of “38.7 million birds killed by rural cats” [13] is based on the results of a study involving just four “urban” cats and one rural cat in Virginia [14, 15] (this, in addition to Coleman and Temple’s several flawed assumptions). And their high estimate was even less valid.

Something else often left out of the debate: predation—even at high levels—does not automati­cally lead to population declines. In fact, some studies [16, 17] have shown that birds killed by cats are, on average, significantly less healthy than those killed through non-predatory events (e.g., collisions with buildings).

In the end, enormous “estimates” of annual predation rates are utterly meaningless—useful only as a sensational talking point by organizations interested in vilifying free-roaming cats. Such figures are routinely “sold” to a mainstream media and public unfamiliar with the larger context.

“…free-roaming cats not only threaten wildlife through direct predation but also serve as vec­tors for a number of diseases including rabies, cat scratch fever, hookworms, roundworms and toxoplasmosis. Some of these diseases can be transmitted to other domestic animals, native wildlife, and in some cases, humans.” [1]

In fact, the CDC site makes no mention of cats being a threat to wildlife. And humans? “Al­though cats can carry diseases and pass them to people, you are not likely to get sick from touch­ing or owning a cat.” And, notes the CDC, “People are probably more likely to get toxoplasmosis from gardening or eating raw meat than from having a pet cat.”

False Premises
The numerous misrepresentations, oversights, and errors outlined above suggest quite clearly that FWS either lacks a sufficient grasp of the critical issues involved—or that it’s not interested in being forthright with the public. This is not an academic issue; nor should my detailed criticism be considered nitpicking. After all, it’s quite clear that FWS intends to eliminate free-roaming cats on public—and, if possible, also private—land throughout the Keys. As “justification for ac­tion,” the IPMP/EA falls well short of what is required; as a public record, it is wholly unaccept­able—and, to be very candid about it—an embarrassment to the agency and the people involved. Simply put, any subsequent action taken by FWS on the basis of this IPMP/EA can, I think, rightfully be considered unjustified.

Moreover, in its attempt to focus on the impacts of cats, FWS overlooks some key factors. As a result, implementation of the IPMP/EA may very well increase the threat to the Keys’ native wildlife.

Mesopredator Release
In its IPMP/EA, FWS refers to two often-cited papers [18, 19] as evidence of cats disrupting native ecosystems, but fails to acknowledge the larger point made by the authors: the mesopreda­tor release phenomenon. “In the absence of large, dominant predators,” write Soulé et al., “smaller omnivores and predators undergo population explosions, sometimes becoming four to 10 times more abundant than normal.” [18]

For Soulé et al., coyotes were the dominant predators, while cats were the mesopredators. In other contexts, however, cats have been shown to play the dominant predator role with non-native rats becoming the mesopredators. [20–23].

Mathematical modeling of the mesopredator release phenomenon illustrates the complexities involved in eradication efforts, even on small islands. As Courchamp et al. explain, “although counter-intuitive, eradication of introduced superpredators, such as feral domestic cats, is not always the best solution to protect endemic prey when introduced mesopredators, such as rats, are also present.” [22] Fan et al. warn of the risks involved with such eradication efforts: “In some cases, it may cause a disastrous impact to managed or natural ecosystems.” [21]

Macquarie Island, located roughly halfway between New Zealand and Antarctica, offers a well-documented example of such a disastrous impact. In 2000, cats were eradicated from this United Nations Educational, Scientific and Cultural Organization World Heritage Site in order to protect its seabird populations. The resulting rebound in rabbit and rodent numbers, however, has had its own disastrous impact. “In response, Federal and State governments in Australia have committed AU$24 million for an integrated rabbit, rat and mouse eradication programme.” [23]

Mesopredator Release in the Keys
But FWS doesn’t even mention the risk of mesopredator release in its IPMP/EA, despite the fact that—should the population of free-roaming cats be sufficiently reduced—the situation in the Keys suggests that such an outcome is actually quite likely. (Because the population and diet of these cats is poorly understood in the Keys, the degree of reduction that would trigger a mesopredator release, too, is unknown.)

According to FWS, non-native rats are already “prevalent in residential and commercial areas.” [1] Should the removal of cats create a spike in their numbers, FWS suggests that they’re prepared to remove the rats, too: “Noticeable population increases based on reports, road kill, or other specific or auxiliary data may initiate targeted control and eradication efforts in addition to incidental capture…” [1]

But controlling these rats is complicated considerably by the need to protect Lower Keys marsh rabbits. The South Florida Multi-Species Recovery Plan (MSRP) warns of these rabbits coming into contact with pesticides and “poisons used to control black rats.” [24]

“In a 1993 Biological Opinion, the FWS investigated the effects of vertebrate control agents on endangered and threatened species and determined that several chemicals (e.g., Pival) would jeopardize the continued existence of the Lower Keys marsh rabbit. Chemicals—such as Pival—a rodenticide used to kill rats, are lethal if ingested. The FWS also concluded that if development in the Keys continues to increase, the potential for these animals to come in contact with such chemicals also increases, as does the potential for their extinction. Based on these findings, the FWS believes the continued use of such chemicals will result in the deaths of Lower Keys marsh rabbits. Given that the majority of occupied habitat is adjacent to urbanized areas, and that urbanization continues to expand into their habitat, then it can reasonably be predicted that the use of such chemicals has had a negative impact upon the Lower Keys marsh rabbit that may prevent its recovery.” [24]

Again, there’s no consideration whatsoever in the IPMP/EA for how the Lower Keys marsh rabbits—the protection of which was a key factor in the creation of the IPMP/EA in the first place—will be protected from increased predatory pressure by non-native rats. Yet, based on the evidence presented by FWS, it’s quite clear that the elimination of free-roaming cats in the Keys will very likely have a negative impact on their numbers—and may very well lead to the extirpation of marsh rabbits from any Key where these rats are present.

The same may be true of the Key Largo cotton mouse [25, 26], Key Largo woodrat [27, 28], and silver rice rat [29, 30], all of which are identified as species of particular concern in the IPMP/EA, and which are threatened—either through predation or competition—by non-native rats such as the black rat.

Alternatives
According to FWS, “the Proposed Action is a fully integrated range of nonlethal and lethal predator management strategies that would be available for implementation on the FKNWRC, depending on the status, distribution, and extent of predation by targeted predator species.” [1] Where feral cats are concerned, however, the “Proposed Action” is nothing more than the “tradi­tional” trap-and-kill approach—this, despite the fact that FWS lacks sufficient data concerning the distribution of, and extent of predation by, feral cats.

FWS is less than forthright on this point, however. According to the IPMP/EA:

“The Monroe County animal control service provider will have the authority to determine the final disposition of the trapped cats according to county ordinances and standards, which may include returning to owner, adopting out, relocating to a long-term cat care facility on the mainland, or euthanizing.” [1]

I asked Connie Christian, Executive Director of the Florida Keys SPCA about this last month. “Every cat brought to our facility is assessed to determine their disposition,” Christian told me via e-mail. “Every attempt is made to return ‘non-feral’ cats to their owners or place for adoption.”

“Unfortunately,” she continued, “we do not have an outlet for feral cats that are brought to us without a request for return.” Which would likely be the case for cats unlucky enough to be trapped by FWS.

(As I understand it, there was a no-kill shelter available at the time of the stakeholder meetings, thus buy-in from those concerned for the welfare of these cats. However, as this is no longer the case (again, this is my understanding of the situation), FWS cannot assume that the same level of buy-in exists today. And in any case, the suggestion of a no-kill shelter or sanctuary as a solution to the Keys’ feral cat issue is at best disingenuous.)

Removing Cats
Setting aside for the moment the issues mentioned above, the IPMP/EA offers little to suggest that FWS will actually be able to remove the free-roaming cats from the Keys. The fact that the agency has no idea how many cats there are is only the beginning. Reports indicate that FWS has a rather poor track record when it comes to trapping cats. Its 2003 contract with USDA, for example, yielded just 23 cats over 31 days of trapping. [32]

In 2007, FWS “received $50,000 to remove cats from federal refuges on Big Pine Key and Key Largo, and to protect endangered marsh rabbits, silver rice rats and other animals and birds that call the refuges home.” [33] Unofficial reports (I’m told nothing official has been issued yet) suggest that fewer than 20 cats were caught—some of which were clearly not feral—along with 81 raccoons, 53 of which were released alive. [34]

I think it’s safe to say that the Keys’ wildlife reaped little or no benefit from either effort. Had the 2007 funding been used for TNR, on the other hand, the impact could have been substantial.

Eradication Efforts
As I’m sure FWS is aware, numerous eradication efforts—the horrors of which are spelled out in some of the papers cited in the IPMP/EA—have been used to successfully remove cats from islands:

Nogales et al., describing the “success” of Marion Island, note, “it took about 15 years of intense effort to eradicate the cats, combining several methods such as trapping, hunting, poi­soning, and disease introduction… The use of disease agents or targeted poisoning campaigns hold promise for an initial population reduction in eradication programs on large islands—such an approach may save effort, time, and money.” [35]

Cruz and Cruz point out that, of all the non-native mammals there, cats were “the most dif­ficult to control or eliminate on Floreana Island.” Although “hunting with dogs was the single most effective method employed and it gave a sure body count,” the authors warn that “the method was costly and with the limited manpower available was only useful over small areas. Both poisoning and trapping were effective and the combination of the three methods is probably the most effective approach, as well as being the best use of time and materials.” [2]

Veitch describes efforts on 11-square-mile Little Barrier Island as “a determined [cat] eradi­cation attempt” involving “cage traps, leg-hold traps, dogs and 1080 poison were used, but leg-hold traps and 1080 poison were the only effective methods.” [35] Four cats were also infected with Feline enteritis, but “because of the poor reaction to the virus no other cats were dosed and none were released… Altogether, 151 cats were known to have been killed before the eradication was declared complete. Important lessons learnt can be transferred to other feral cat eradication programmes.” [36] (By way of comparison, the Keys are approximately 137 square miles in total area.)

As FWS notes in its IPMP/EA, such methods are “not… socially acceptable” and “inconsistent with the points of consensus developed by the stakeholder group.” While I agree completely that these methods are unacceptable, the “fully integrated range of nonlethal and lethal predator man­agement strategies” proposed by FWS strike me as nothing more than business as usual. How will this be any different (other than perhaps in terms of scale) than the failed efforts of the past?

If implemented as-planned, it seems clear that FWS will not be able to remove the cats quickly enough to keep up with reproduction rates. Using a population model, Andersen, Martin, and Roemer have suggested that, in the absence of a sterilization program, 50 percent of cats would have to be removed in order for a colony to decrease 10 percent annually. [37] This model has its flaws (some of which are described in “Reassessment”) but even if Andersen et al. are off by a factor of two, FWS would need to remove 25 per­cent of the free-roaming, unsterilized (and in the absence of TNR, it won’t be long before that’s the norm) cats continuously in order to achieve a modest 10 percent annual reduction in overall numbers.

Does anybody at FWS really think that’s going to happen? Where’s the evidence to suggest that it’s even possible?

If the feeding of feral cats and TNR are eliminated (to whatever extent possible) throughout the Keys, these cats will simply “go underground.” That means no more monitoring—and steriliz­ing—by the “foot soldiers” who currently care for them.

Indeed, it’s quite likely that feral cat complaint calls to Monroe County, FWS, and USDA would taper off considerably, as it becomes clear that such a call is essentially a death sentence. Thus, the cats would become that much more difficult to locate—and sterilize. The population, there­fore, would increase—probably very quickly.

In other words, the most likely outcome of the IPMP/EA put forward by FWS is an increase in the number of feral cats in the Keys—and, of course, a corresponding increase in the negative impacts they have on the area’s wildlife and environment.

Trap-Neuter-Return
In contrast to the IPMP/EA—with its risk of mesopredator release, on the one hand, and poten­tial to inadvertently drive up the numbers of feral cats, on the other—TNR offers the potential to more carefully manage the population of feral cats in the Keys. Indeed, given the precarious nature of wildlife in the Keys, TNR may actually be the best approach to fulfill the purpose of the IPMP/EA:

“…conserve and restore federally-listed species and protect all native fauna and flora on the [refuges] from population decline and potential extirpation or extinction due to predation by non-native species and human-subsidized populations of native predators.” [1]

The fact that TNR was “considered but dismissed from further evaluation,” again, suggests that FWS failed to adequately analyze all of the available predator management alternatives. And, similar to its “justification for action,” FWS’s rationale for dismissing TNR doesn’t hold up to scrutiny.

FWS argues, for example, that TNR “does little to reduce cat predation on native wildlife.” Al­though few predation studies have examined the hunting behavior of cats belonging to managed colonies, those that have are revealing. Reporting on their study of free-roaming cats in Brook­lyn, Calhoon and Haspel write: “Although birds and small rodents are plentiful in the study area, only once in more than 180 [hours] of observations did we observe predation.” [38]

And Castillo and Clarke (though highly critical of TNR) actually documented remarkably little predation in the two Florida parks they used for their study. In fact, over the course of approximately 300 hours of observation (this, in addition to “several months identifying, describing, and photographing each of the cats living in the colonies” [39] prior to beginning their research), Castillo and Clarke “saw cats kill a juvenile common yellowthroat and a blue jay. Cats also caught and ate green anoles, bark anoles, and brown anoles. In addition, we found the carcasses of a gray catbird and a juvenile opossum in the feeding area.” [39]

“In addition,” argues FWS, “the TNR method has little valid scientific support for claims that it actually reduces cat colony numbers over time and often has been shown to attract people to release new cats into an area.” [1] Ironically, some of the greatest TNR success stories are right there in the papers cited by FWS. Natoli, for example, reported a 16–32 percent decrease in population size over a 10-year period across 103 colonies in Rome—despite a 21 percent rate of “cat immigration.” [40] And, as of 2004, ORCAT, run by the Ocean Reef Community Associa­tion, had reduced its “overall population from approximately 2,000 cats to 500 cats.” [41] Accord­ing to the ORCAT website, the population today is approximately 350, of which only about 250 are free-roaming.

Any TNR program contends with the unfortunate (and illegal) dumping of cats. Still, it’s difficult to imagine that the presence or absence of a nearby TNR program would affect a person’s decision to abandon his/her pet cat(s). (If any studies had demonstrated such a connection, TNR opponents would surely cite them.) On the other hand, cats dumped near a managed colony are far more likely to be adopted and/or sterilized—thereby mitigating their potential impact on the overall population of unowned cats—as well any impacts to wildlife and the environment.

ESA and MBTA
Among the more perplexing aspects of FWS’s argument is their claim that “TNR practices are prohibited on National Wildlife Refuges, and violate the Endangered Species Act (ESA) and the Migratory Bird Treaty Act (MBTA) because they may result in the direct harm of protected species.”

This is an argument that’s been thrown around since at least 2003, when Pamela Jo Hatley, then a law student, suggested the possibility. But that’s all it was—and, apparently, is—a possibility.

“It is quite obvious that cats can be lethal to birds,” writes Hatley, “and if the death of a migratory bird can be traced to a cat, or a cat colony, which can be further traced to an individual or orga­nization, there may be strict liability for that person under the MBTA.” [43] Hatley’s argument for violations of the Endangered Species Act is similarly speculative: “…persons who release cats into the wild or who maintain feral cat colonies could be found liable for a take under section 9 of the ESA if maintenance of feral cats in the wild is found to kill or injure wildlife by degrading habitat.” [43]

Summary
There is no doubt that the Florida Keys are immensely valuable for their diversity of animal and plant life, some of which can be found nowhere else in the world. Due to a wide range of fac­tors—most of them human-caused—this habitat has become quite fragile, with some animal and plant species on the brink of extinction. Ecosystems—especially those as fragile as the Keys—are incomprehensibly complex, and tinkering with them is incredibly risky. And there’s plenty we simply do not know, and cannot—despite our best efforts—predict.

In its attempt to eliminate free-roaming cats from the Keys, FWS overlooks several important factors, thereby imposing a greater risk to the very native wildlife it aims to protect.

The IPMP/EA proposed by FWS fails to adequately address (1) the presumed impacts of free-roaming cats on native wildlife in the Keys, and (2) the risks inherent with the improper man­agement of these cats. It’s easy to imagine the losers in the deal—the cats, obviously, but also all of the wildlife FWS wants to protect. And the taxpayers, too, of course—this promises to be a dismal return on investment for all of us, no matter what our position might be on feral cats, wildlife conservation, and the like. The question is, where are the winners?

I strongly encourage FWS to revise its IPMP/EA, paying particular attention to these two issues, and to give further consideration to TNR in light of these and other important factors outlined in this letter.

11. Sax, D.F. and Gaines, S.D., Species invasions and extinction: The future of native biodiversity on islands, in In the Light of Evolution II: Biodiversity and Extinction,. 2008: Irvine, CA. p. 11490–11497. www.pnas.org/content/105/suppl.1/11490.full

Over the past year, “Critical Assessment” has gotten a great deal of traction among TNR opponents, despite its glaring omissions, blatant misrepresenta­tions, and obvious bias. “Reassessment”—intended to be a resource for a broad audience, including, wildlife and animal control professionals, policymakers, and the general public—shines a bright spotlight on these shortcomings, thereby bringing the key issues back into focus.

Act Locally
Politics is, as they say, local. This is certainly true of the debate surrounding TNR. Policies endorsing TNR, the feeding of feral cats, etc. typically begin with “Town Hall” meetings, or even meetings of neighborhood associations. “Reassessment” provides interested parties with a rigorous, science-based counter-argument to those using “Critical Assessment” as a weapon against feral cats/TNR.

So, once you’ve had a look for yourself, please share generously! Together, we can—in keeping with the mission of Vox Felina—improve the lives of feral cats through a more informed, conscientious discussion of feral cat issues in general, and TNR in particular.

For years now, the American Bird Conservancy (ABC) has been promoting erroneous and misleading information in their tireless effort to vilify free-roaming cats. No organization has been more effective at working the anti-TNR pseudoscience into a message neatly packaged for the mainstream media, and eventual consumption by the general public. Speaking to the Wall Street Journal in 2002, Becky Robinson, co-founder and President of Alley Cat Allies, described ABC’s Cats Indoors! campaign as “a new environmental witch hunt.” [1]

In their recently released book, The American Bird Conservancy Guide to Bird Conservation, ABC changes tack a bit—using what the authors call “conservative” estimates of the outdoor cat population and annual predation rates, for example, to arrive at their figure of “532 million birds killed annually by outdoor cats.” [2] At the same time, they include much of the same misinformation ABC’s been promoting all along. It’s a clever strategy, really: endorsing bogus claims as valid science without having to defend them as such.

In fact, one doesn’t need to get past the book’s preface before realizing the role that science plays—or, more to the point, doesn’t play—at ABC. “We see very few issues resolved through coming to consensus on the science,” writes President and CEO George Fenwick.

“More often, science divides us. So, though we continue to need excellent science, conservationists also need to learn how to better persuade, use media effectively, and connect birds to the human condition, spirituality and ethical values.” [2]

If its section on cats is any indication, The ABC Guide is the manifestation of Fenwick’s philosophy: more style than substance, more sales than science. The authors didn’t even bother with citations and references, suggesting to readers, perhaps, that The ABC Guide is the last word on the subject. Where free-roaming cats are concerned, though, ABC has precious few answers—in part because they (still) aren’t asking the right questions.

Outdoor Cats
Referring to unattributed 2007 data, the authors of The ABC Guide—Daniel Lebbin, Michael Parr, and George Fenwick—claim that 43 percent of pet cats “have access to the outdoors.” [2] But, according to American Pet Products Association (APPA) 2008 National Pet Owners Survey, 64 percent of cats are indoor-only during the daytime, and 69 percent are kept in at night [3].

Other surveys have yielded similar results, and also indicate that, of those cats that are allowed outdoors, approximately half were outside for three hours or less each day [4, 5]. For Lebbin et al., though, these part-timers are no different from their feral relatives. Of which, “there are 60–120 million,” according to the authors. [2]

Where this figure comes from is anybody’s guess. It’s substantially higher than any other estimates I’ve seen, with one notable exception—a statement made earlier this year by an ABC official (more on that in a moment).

Feral Cat Numbers
Very little exists in terms of credible population estimates for feral cats. There are, however, many unsubstantiated claims.

Among the most popular for those interested in big numbers is the first line from David Jessup’s ironically titled 2004 paper “The welfare of feral cats and wildlife” (ironic because his “concerns” for the welfare of these cats are so plainly disingenuous): “There are an estimated 60 to 100 million feral and abandoned cats in the United States.” [6] As to the origins of Jessup’s “estimate,” again, it’s anybody’s guess, as he offers no reference.

Based on the results of a 1999 telephone survey of Alachua County, Florida, residents, Levy et al. estimated that the population of free-roaming cats represented approximately 44 percent of the county’s total population of cats. [7] Other researchers have reported similar figures for nationwide estimates. [8] By way of comparison, ABC’s estimate represents 39–56 percent of the overall population of cats in the U.S. (based on APPA’s latest figures for pet cats).

Dauphine and Cooper begin their adventure in creative accounting with Jessup’s unattributed 100 million, and add to it the number of owned cats they describe as “free-ranging outdoor cats for at least some portion of the day.” [11] For which they turn to Linda Winter, former director of Cats Indoors!, and her 2004 paper in which she reports the findings of a 1997 telephone survey (commissioned by ABC) of cat owners. According to Winter, “66 percent of cat owners let their cats outdoors some or all of the time.” [12]

In fact, the survey—as reported in ABC’s brochure “Human Attitudes and Behavior Regarding Cats”—indicated that “35 percent keep their cats indoors all of the time” and “31 percent keep them indoors mostly with some outside access.” [9] The difference in wording is subtle and hampered by imprecision (it all comes down to the meaning of some), but it’s difficult not to see this as deliberately misleading on Winter’s part.

In any case, results of other surveys (described previously) suggest quite convincingly that outdoor access for the vast majority of pet cats is really very limited. Nevertheless, Dauphine and Cooper persist, arriving at a staggering “117–157 million free-ranging cats.” [11] Holmer, in turn, rounds off the upper limit, “scrubs” the pet cats from the calculation by calling them all ferals, and gets the bogus figure printed in the Times. (Gold star for Holmer!)

Lebbin et al. don’t go that far, but their “most conservative estimate of outdoor and feral cats in the U.S.”—95 million—is, given its shaky origins, no more valid than Dauphine and Cooper’s.

Predation
According to The ABC Guide, “all outdoor cats hunt and kill birds (20­–30 percent of cat prey) and other small animals.” [2] No study I’m aware of has demonstrated that all cats hunt. On the contrary, some research suggests that less than half of outdoor cats hunt. Figures as low as 36–56 percent have been reported by researchers in Australia, for example. [13]

In the UK, Baker, Bentley, Ansell, and Harris reported that 77 cats returned a total of 212 prey items to 52 Bristol households participating in their pilot study, but “in each sampling period, the majority of cats (51–74 percent) failed to return any prey.” [14] The subsequent 12-month study (this time involving 186 Bristol households, 275 cats, and 495 prey items) found a similar level of apparent non-hunters: roughly 61 percent. [15]

Woods, McDonald, and Harris, also working in the UK, found that, although 91 percent of cats returned at least one item, “approximately 20–30 percent of cats brought home either no birds or no mammals.” [16] And Churcher and Lawton’s yearlong “English Village” study (involving approximately 70 cats and 1,090 documented prey items) found that that 8.6 percent of cats brought home no prey [17] (though the authors don’t specify the percentage of cats that returned no birds).

The Diet of Cats
The idea that birds make up 20–30 percent of the diet of free-roaming cats is one that ABC has been promoting since 1997, when they launched Cats Indoors! But it’s no more valid now than it was then.

According to ABC’s brochure, “Domestic Cat Predation on Birds and Other Wildlife” (downloadable from their website), “extensive studies of the feeding habits of domestic, free-roaming cats… show that approximately… 20 to 30 percent [of their diet] are birds.” Ellen Perry Berkeley carefully examined—and debunked—this claim in her book, TNR Past Present and Future: A history of the trap-neuter-return movement, noting that ABC’s 20–30 percent figure wasn’t based on “extensive studies” at all. [10]

As Berkeley points out, combining or comparing data from these three sources is entirely inappropriate. Both the English Village and Wisconsin studies report the percentage of birds returned as a portion of the “total catch,” whereas Fitzgerald reports percentage by frequency (i.e., the occurrence of birds in the stomach contents or scats of free-roaming cats).

To put this into more familiar terms, consider coffee consumption. According to the 2009 National Coffee Drinking Trends Study, 54 percent of American adults drink coffee daily—54, then, is the percentage by frequency. To say that coffee makes up 54 percent of our dietary intake—essentially ABC’s interpretation—is obviously a gross exaggeration of consumption levels. (Neither measure says anything about the supply of coffee, of course.)

Nevertheless, 13 years after ABC first published its report—and six years after Berkeley exposed the error publicly in TNR—the myth persists. So much for ABC’s commitment, spelled out in the book’s section on threats, to “address all of the major threats responsible for killing large numbers of birds, using the best information and research available, while promoting further research and monitoring where it is most needed.” [2]

Which, in turn, raises serious questions about the integrity of ABC and the people running it.

“There were seven declawed cats in the study and all but one took birds (giving a figure of 86 percent); the top predator cat was declawed. Declawing cats appears to have no effect whatsoever on the ability to hunt birds.” [18]

But, both ABC and Fiore leave out some critical details. There were, after all, only 41 cats involved in the study—hardly the kind of sampling required to make such sweeping statements.

A closer look reveals that the declawed cats were apparently responsible for killing an average of 3.6 birds/cat/year while the cats with claws had an average of 3.0. Does this mean that the declawed cats are actually superior hunters compared to the other cats? Hardly.

In addition to the sampling issue, there’s the problem inherent in using the average to describe highly skewed distributions (many cats catching few prey, while few cats catch many prey). In such instances, it’s more appropriate to use median values, which better represent “average” hunting success. [20] Doing so yields estimates of 1 bird/cat/year for the declawed cats vs. 2 birds/cat/year for the cats with claws.

So, declawed cats kill only half as many birds as those with claws? I’ll leave such indefensible claims to others.

Now, to be clear: I’m no advocate of declawing. Nor do I think it’s in the best interest of pet cats to be outdoors—especially those without claws. My point here is merely to demonstrate the flaws in ABC’s deceptively straightforward assertion; once again, ABC is more interested in a good story than they are in good science. (Their comment about declawed cats is precisely the kind of sound-bite that is easily picked up by the media, and repeated so widely that it becomes nearly impossible to trace—never mind untangle.)

Cats and Birds
As evidence of the “variable predation rates by cats,” [2] The ABC Guide refers to just four studies. And, although no citations are included, people familiar with the literature will recognize the numbers and locations immediately.

Another of the predation rates included in The ABC Guide is the more moderate 15 birds/cat/year from Crooks and Soulé’s 1999 paper [22]. But here, too, there are flaws that lead to bloated predation levels.Like Lepczyk, Crooks and Soulé asked residents to estimate annual levels of prey returned home by their cats (in contrast to some studies in which actual prey items are recorded and/or collected). But such guesswork becomes less accurate as estimates increase. David Barratt found that “predicted rates of predation greater than about ten prey per year generally over-estimated predation observed” [20]. At the levels reported by Crooks and Soulé—an average of 56 total prey items (including birds, mammals, etc.) per year—predicted rates were often twice actual predation rates.

Also, Crooks and Soulé seem (not enough detail is provided in their paper to be certain) to have used a simple average in their calculations, perhaps doubling true predation levels. Taken together, these factors suggest that actual predation levels might be just a quarter of those suggested by Crooks and Soulé.

The third study—easily the most rigorous of the four—with a predation rate of 9.6 birds/cat/year, comes from Woods et al. The researchers, having recruited study participants solely from The Mammal Society, allow that they “may have focused on predatory cats,” and ask that their results be “treated with requisite caution.” [16] They also make clear that their estimated predation rates “do not equate to an assessment of the impact of cats on wildlife populations” [16] (more on that shortly)

Finally, there is the—seemingly inevitable—reference to the Wisconsin Study, though for some reason (again, without explanation) Lebbin et al. have adjusted Coleman and Temple’s figures of 28–365 birds/cat/year downward: “between 5.6 and 109.5.” [2]In this case, the details hardly matter. The Wisconsin Study isn’t actually a study at all; no predation data or findings were ever published. Coleman and Temple’s “estimates”—widely circulated as valid research, thanks in part to ABC—were nothing more than back-of-the-envelope calculations. “Our best guesses,” as the authors themselves admit, “at low, intermediate and high estimates of the number of birds killed annually by rural cats in Wisconsin.” [23]

“Those figures were from our proposal,” Temple told The Sonoma County Independent. “They aren’t actual data; that was just our projection to show how bad it might be.” [24]

Sixteen years later, though, ABC is still trying to make “actual data” out of “not actual data.” (Granted, they have backed off from Coleman and Temple’s high estimate, but no mathematical adjustments can transform these flawed, biased guesses into valid research findings.)

Cats as Hunters
Contrary to popular myth, evidence suggests that cats are not quite the hunters they’ve been made out to be. Fitzgerald and Turner suggest that the hunting behavior of cats leads to many “failures,” and, as a result, “many cats soon give up bird hunting altogether.” [25]

“Primarily, all cats hunt both birds and rodents with equal zeal,” observed German zoologist Paul Leyhausen, “and many obviously prefer eating birds.” But, argues Leyhausen (1916–1998), who spent the bulk of his career studying the behavior of cats, “they cannot catch them as easily, and for this reason with increasing experience may soon give up hunting birds.” [26]

“However, our town cats today are often compelled, because of the almost total absence of rodents in their territory to concentrate on chasing birds in order to discharge their pent-up hunting propensities. Even in these circumstances, however, cats are not capable of seriously endangering the songbird population of a substantial area. They almost always catch only old, sick or young specimens. But three quarters of the young birds must perish anyway, since the size of the population in an area remains fairly constant on an average over the years… During years in the field I have observed countless times how cats have caught a mouse or a rat and just as often how they have stalked a bird. But I never saw them catch a healthy songbird that was capable of flying. Certainly it does happen, but, as I have said, seldom. I should feel sorry for the average domestic cat that had to live solely on catching birds.” [26]

Although few predation studies have examined the hunting behavior of cats belonging to managed colonies, those that have are revealing. Reporting on their study of free-roaming cats in Brooklyn, Calhoon and Haspel write: “Although birds and small rodents are plentiful in the study area, only once in more than 180 [hours] of observations did we observe predation.” [27]

Castillo and Clarke, though highly critical of TNR (“This method is not an effective means to control the population of unwanted cats and confirms that the establishment of cat colonies on public lands encourages illegal dumping and creates an attractive nuisance.” [28]), documented little predation in the two Florida parks they used for their study (the focus of which was TNR efficacy, not predation). Over the course of approximately 300 hours of observation (this, in addition to “several months identifying, describing, and photographing each of the cats living in the colonies” [28] prior to beginning their research), Castillo and Clarke “saw cats kill a juvenile common yellowthroat and a blue jay.” [28]

“Cats also caught and ate green anoles, bark anoles, and brown anoles. In addition, we found the carcasses of a gray catbird and a juvenile opossum in the feeding area.” [28]

Another study conducted in a public park, this one in Alameda County, California, also reported low levels of apparent predation of birds (though researcher Cole Hawkins makes every attempt to suggest otherwise). Of 120 scat samples found by searching the “cat area” of Hawkins’ study site, “65 percent were found to contain rodent hair and 4 percent feathers.” [2] This finding comes toward the end of the study, when the cat population was at its greatest (22 were sighted)—and still, only 4 percent contained feathers. And this could easily represent one cat and one bird (and, strictly speaking, even this is not evidence of actual predation, as the bird(s) could have been scavenged).

Impact
To arrive at their figure of “532 million birds killed annually by outdoor cats,” Lebbin et al. multiply “the most conservative predation rate (5.6 birds per cats per year) by the most conservative estimate of outdoor and feral cats in the U.S. (95 million).” [2] They go on to suggest that “the actual number” is “likely… much higher,” [2] though, of course, they ignore or overlook all the errors and misrepresentations bound up in their basic calculation.

Even setting all that aside, the question remains: What impact does predation by cats have on bird populations?

Islands and Continents
Here, the authors focus mostly on the extinction of seabirds linked to the presence of feral cats on islands. I’m only vaguely familiar with the examples they cite, but if the case of the Stephens Island Wren is any indication, the stories are far more complex than ABC suggests. [see, for example, 29 and 30]

But, as Fitzgerald and Turner point out, “because the range of prey available on islands differs markedly from that on the continents the two groups, continents and islands, are treated separately.” [25]

And when it comes to the impact of cats on continental bird populations, ABC highlights rare and endangered species—but ignores entirely two key points. First, as was mentioned previously, even high rates of predation do not equate to population declines.

Referring to the estimated 30 percent of House Sparrow mortality attributed to cat predation in the English Village study, Gary Patronek emphasizes the importance of viewing such predation in the larger context. “When the birds were counted,” writes Patronek, former Director of the Center for Animals and Public Policy at the Cummings School, and one of the founders of the Hoarding of Animals Research Consortium, “they represented the postwinter population prior to hatching of spring chicks. By the year’s end, the actual sparrow population in the village numbered in the thousands, and the 130 birds caught represented about 5 percent of that number.” [31]

Compensatory vs. Additive Predation
Then there is the critical distinction between compensatory and additive predation, something Churcher himself alluded to: “I don’t really go along with the idea of cats being a threat to wildlife. If the cats weren’t there, something else would be killing the sparrows or otherwise preventing them from breeding.” [32]

Two very interesting studies have generated compelling evidence that birds killed by cats are, on average, significantly less healthy than those killed through non-predatory events (e.g., collisions with buildings). [15, 33] In other words, these birds probably weren’t going to live long enough to contribute to the overall population numbers; predation was compensatory rather than additive. Relative to population impacts, then, the “accounting” of bird kills is far more complex than ABC suggests.

Additional Evidence
Many researchers have disputed the kind of broad, overreaching claims Lebbin et al. make about the impact of cats on bird population (and wildlife in general).

Biologist C.J. Mead, reviewing the deaths of “ringed” (banded) birds reported by the British public, suggests that cats may be responsible for 6.2–31.3 percent of bird deaths. “Overall,” writes Mead, “it is clear that cat predation is a significant cause of death for most of the species examined.” Nevertheless, Mead concludes:

“there is no clear evidence of cats threatening to harm the overall population level of any particular species… Indeed, cats have been kept as pets for many years and hundreds of generations of birds breeding in suburban and rural areas have had to contend with their predatory intentions.” [34]

Mike Fitzgerald and Dennis Turner come to essentially the same conclusion: “We consider that we do not have enough information yet to attempt to estimate on average how many birds a cat kills each year. And there are few, if any studies apart from island ones that actually demonstrate that cats have reduced bird populations.” [25]

In the context of TNR, however, focusing on such figures may be missing the point. “If the real objection to managed colonies is that it is unethical to put cats in a situation where they could potentially kill any wild creature,” writes Patronek, “then the ethical issue should be debated on its own merits without burdening the discussion with highly speculative numerical estimates for either wildlife mortality or cat predation.” [35]

“Whittling down guesses or extrapolations from limited observations by a factor of 10 or even 100 does not make these estimates any more credible, and the fact that they are the best available data is not sufficient to justify their use when the consequence may be extermination for cats… What I find inconsistent in an otherwise scientific debate about biodiversity is how indictment of cats has been pursued almost in spite of the evidence, and without regard to the differential effects of cats in carefully selected, managed colonies, versus that of free-roaming pets, owned farm cats, or truly feral animals. Assessment of well-being for any species is an imprecise and contentious process at best. Additional research is clearly needed concerning the welfare of these cats.” [35]

Trap-Neuter-Return
“Many well-intentioned but misguided people,” write Lebbin et al. “exacerbate feral cat problems through a technique called Trap, Neuter, Release (TNR), whereby colony cats are caught, spayed or neutered, and then returned to colonies to be fed by volunteers.” [2] Here, the authors trot out a classic verbal swipe, using the term Release instead of Return, implying a certain lack of planning, or even abandonment (with its legal implications).

“Despite its apparent appeal,” Lebbin et al. continue, “few colonies managed under this system shrink, as the program takes more time than most volunteers are able to give, some cats are never caught, and the colonies often become dumping grounds for more unwanted cats.” [2]

Resources
Their claim that TNR programs are ineffective due to limited resources is unsubstantiated. More important, though, they ignore the fact that any feral cat management program is resource-intensive (as is any conservation effort, of course). Several successful TNR programs have been documented (see below), and countless more operate quietly, out of the spotlight.

It’s important to point out, too, that TNR is typically funded through private donations and the out-of-pocket purchases of volunteers. Trap-and-kill, on the other hand, is more likely to rely entirely on local tax dollars.

Sterilization
Their suggestion that all the cats need to be sterilized also lacks support. One often-cited population modeling study—included here more as a reference point than anything else—found that, in order to reduce colony population, approximately 75 percent of fertile cats would need to be sterilized. [36] However, this figure from Andersen, Martin, and Roemer takes into account no adoptions, though the authors point out that adoptions “are similar in effect to euthanasia because these cats are permanently removed from the free-roaming cat population.” [36]

Nor do Andersen et al. consider emigration between cat colonies, though they concede that “a substantial number of owned cats are reported to be adopted strays.” [36] “Substantial” is right—in 2003, Clifton suggested that “up to a third of all pet cats now appear to be recruited from the feral population.” [10]

TNR Successes
Though Lebbin et al. refuse to acknowledge it, TNR has had its share of successes. A 10-year TNR program in Rome, for example, yielded a “16–32 percent decrease on total cat number” across 103 managed colonies. [37] Detractors [38] like to focus on authors’ suggestion that “all these efforts without an effective education of people to control the reproduction of house cats (as a prevention for abandonment) are a waste of money, time and energy.” [37]

Levy, Gale, and Gale reported a 66 percent decline in the population of managed colonies on the University of Central Florida campus between 1991 and 2002, despite the arrival of stray or abandoned cats. [40] (In their paper, Levy et al. cite several other success stories.) And, in their telephone survey of 101 north-central Florida colony caretakers, Centonze and Levy reported “a 27 percent decrease in mean colony size within less than one year of beginning neutering.” [41]

One of the best-known TNR programs is ORCAT, run by the Ocean Reef Community Association, which, according to a 2004 paper, had reduced “overall population from approximately 2,000 cats to 500 cats.” [42] According to the ORCAT website, the population today is approximately 350, of which only about 250 are free-roaming.

Any TNR program contends with the unfortunate (and illegal) dumping of cats. But to suggest that TNR invites abandonment of cats is ridiculous. I’ve seen no research supporting such a claim. If people are determined to abandon their pet cat(s), I fail to see how the presence or absence of a nearby TNR program will affect that decision. On the other hand, cats dumped near a managed colony are far more likely to be adopted and/or sterilized—thereby mitigating their potential impact on the overall population of unowned cats.

Finally, it’s important to note that, although rapid decline—and eventual elimination through attrition—of managed colonies is the goal of TNR (and apparently the only acceptable outcome for the authors of The ABC Guide), reduced growth is not without its benefits. “Population stabilization,” writes Levy, is “a valid metric given that the status quo for unsterilized cats is rapid population growth.” [39]

Alternatives to TNR
Given their ongoing criticism of TNR, one might expect ABC to offer an alternative method of feral cat management—an approach against which to measure TNR (and against which TNR would, presumably, prove inferior). For the most part, though, ABC sidesteps the issue.

“Neutering and spaying pet cats,” write Lebbin et al., “is a humane method for reducing cat over-population.” True enough, but that doesn’t address the sizable population of unowned cats. Although The ABC Guide calls for readers to “make TNR and the feeding of cat colonies illegal,” [2] there’s no recommendation for what should be done with all of these cats.

I put this question to Lebbin and Parr during an ABC webinar celebrating the launch of the book earlier this month. “What we recommend,” said Parr, Vice President of ABC, “as an alternative to [TNR], is not abandoning cats in the first place.” Again, I don’t think there’s any disagreement on this point. Parr continued:

“Other options would be to house those cats in shelters or outdoor sanctuaries which could be managed. Clearly, it’s a huge problem, and the solutions to this are going be things we going to have to work together on for a long period of time, but certainly that would be my first reaction to that question.”

Trap-and-Remove
In their book, Lebbin et al. point out, with obvious pride, that, “By 2004, feral cats had been successfully removed from at least 48 islands worldwide” (there’s another euphemism: removed). [2] A particular “success” is Ascension Island, where, the authors maintain, feral cats had reduced seabird numbers “by 98 percent, from 200 million to 400,000.” [2] As a result of “a multi-year eradication effort that began in 2001,” [2] birds have begun to return.

But, as is often the case, what’s left out of the story is far more interesting than what included.

Detailed accounts of feral cats eradication Marion Island provide a glimpse of the horrors involved. A 1992 paper reports 872 cats shot and 80 more trapped during 14,725 hours of hunting. “Present action” included “mass trapping and poisoning, and the possible use of trained dogs [was] being investigated.” [43] This was after the highly contagious feline panleucopenia virus (feline distemper) had been introduced to the island’s feral cat population, reducing the population by an average 29 percent annually between 1977 and 1982. [44]

On Macquarie Island successful eradication has had “dire” [45] consequences in the form of rapidly increasing rabbit and rodent populations. “In response, Federal and State governments in Australia have committed AU$24 million for an integrated rabbit, rat and mouse eradication programme.” [45]

Given the extent to which conservation efforts backfired on Macquarie Island—less than 50 square miles in size—one can only imagine the consequences and expense (to say nothing of the protests!) of a similar attempt in the continental U.S. But according to ABC, it seems to be either this or sanctuaries—for a population of feral cats they claim to be 60–120 million strong.

(To be fair, Lebbin et al. do offer this concession: “In some cases, invasive or overabundant species may not need to be eradicated, but simply reduced to levels such that they no longer pose a serious threat to native endangered species.” [2] Given their staunch opposition to TNR, however, I suspect this “offer”—which in any case would mean the killing of many millions of cats—does not apply to feral cats.)

The Current Approach
We do have some sense of how ineffective “traditional” feral cat management—a mix of trap-and-kill and inaction—has been. In an interview with Animal Sheltering magazine, Mark Kumpf, President of the National Animal Control Association President from 2007 to 2008, described this approach as “bailing the ocean with a thimble,” suggesting, too, that “the traditional methods that many communities use… are not necessarily the ones that communities are looking for today.” [46]

Clifton goes further, suggesting that trap-and-kill has actually backfired: “Regardless of motive,” writes Clifton, “the effect on the feral cat population replicates natural predation: the most frequent victims are the very young, the old, the disabled, and the ill. The healthiest animals usually escape to breed up to the carrying capacity of the habitat, if they can.” [10]

“Responding to the intensified mortality,” Clifton continues, “felis catus now bears an average litter of four. Nearly seven centuries of killing cats doubled the fecundity of the species.” [10]

Accountability
What Becky Robinson called a “new environmental witch hunt,” [1] I like to think of as a Trojan Horse. Disguised as good advice for responsible cat owners, ABC’s Cats Indoors! campaign has, since 1997, been used more to combat TNR than anything else.

With the publication of The ABC Guide, the authors had a chance to right some past wrongs by coming clean about the research surrounding predation, wildlife impacts, and TNR, as well as the true implications of their call to “make TNR and the feeding of cat colonies illegal.” [2] Instead, they elected for business as usual.

But Fenwick, who’s been President and CEO since ABC’s founding in 1994, doesn’t seem to get it. “What have we learned about the opposition?” he asks rhetorically in the book’s preface.

“For one thing, every point of view has its own science and economics to support its contentions, whether it be pro- or anti- pesticide use, free-roaming cats, bird collisions with glass or towers, conflicts with fisheries, land conversion, wind energy, mining, timbering, climate change, or any other issue we consider in addressing bird conservation…” [2]

Fenwick seems to be suggesting that “the opposition” has its own science and economics, whereas ABC has, on its side: Science and Economics (a truly untenable position, in light of a recent ABC press release).

“Facts alone will not win these battles,” he continues, “but human connection might.”

Communication vs. Misinformation
I have to agree with Fenwick that facts alone are insufficient to engage the general public. It’s difficult, for instance, to convey the critical nature of climate change in terms of ocean temperatures rising a couple of degrees Celsius (a figure I use here only to make a point). Explain to people how deep the water may rise in their city or neighborhood, however, and you’re liable to get their attention.

But that’s not what ABC is doing. They have effectively dismissed any and all rigorous science, choosing instead to broadcast as loudly as possible their increasingly dire message—in spite of the science.

Fenwick’s analogy is not climate change, but human health and welfare:

“…no matter the issue, our opposition will unfailingly question our priorities. So, they ask, ‘Why are you blaming __________ when we know habitat loss is the real problem?’ when I am asked these questions, I reply first that we continue to add to our base of knowledge and thus improve decisions affecting bird populations; second, if winning the debate translates to financial gain for the debater, then that position cannot be truly unbiased; and third, isn’t it analogous that if heart disease is the greatest mortality factor in our species, then why do we spend so much money combating cancer and other diseases, poverty and hunger? Solving any single problem—for birds or humans—is insufficient for our cause. Thoughtful people understand that it is critical that we fight for birds and humans across the full, broad front of issues.” [2]

“The article spelled out his belief that researchers were frequently manipulating data analyses, chasing career-advancing findings rather than good science, and even using the peer-review process—in which journals ask researchers to help decide which studies to publish—to suppress opposing views.” [47]

Obviously not the image Fenwick was trying to convey—but far more fitting.

Attacking “the full, broad front of issues” simultaneously makes perfect sense, but promoting erroneous and deceptive scientific claims in order to marshal the support necessary is unethical, plain and simple.

We’re not talking about cancer research distracting us from research into heart disease, to use Fenwick’s metaphor. No, what he and ABC are doing—in their relentless persecution of free-roaming cats, at least—is akin to funneling critical resources into the bottling and marketing of snake oil:

There’s no science behind it, and no remedy in its consumption—whatever the dosage.

7. Levy, J.K., et al., “Number of unowned free-roaming cats in a college community in the southern United States and characteristics of community residents who feed them.”Journal of the American Veterinary Medical Association. 2003. 223(2): p. 202-205. http://avmajournals.avma.org/doi/abs/10.2460/javma.2003.223.202

18. Fiore, C.A., The Ecological Implications of Urban Domestic Cat (Felis catus) Predation on Birds In the City of Wichita, Kansas, in College of Liberal Arts and Sciences. 2000, Wichita State University: Wichita, Kansas.

That’s what somebody posted on the Vox Felina Facebook page late last night—along with a link to an MSNBC news story. The headline was an attention-getter, no doubt about it: “Report: Kill feral cats to control their colonies.”

“The report began in an undergraduate wildlife management class, with students writing reports on feral cats based on existing research. The students’ professor and other [University of Nebraska] researchers then compiled the report from the students’ work.” [1]

“Feral Cats and Their Management” claims, straightforwardly enough, to provide “research-based information on the management of feral cats.” [2] Management, in this case, meaning—as is so often the case in such contexts—killing, extermination, eradication, and so forth. Detailed advice is provided (e.g., “Body-gripping traps and snares can be used to quickly kill feral cats”).

It’s no surprise that the authors of the report offer no evidence to support such a sweeping claim. “There are few if any studies,” write Mike Fitzgerald and Dennis Turner in their contribution to The Domestic Cat: The biology of its behaviour, “apart from island ones that actually demonstrate that cats have reduced bird populations.” [3]

Biologist C.J. Mead, reviewing the deaths of “ringed” (banded) birds reported by the British public, suggests that cats may be responsible for 6.2–31.3% of bird deaths. “Overall,” writes Mead, “it is clear that cat predation is a significant cause of death for most of the species examined.” Nevertheless, Mead concludes, “there is no clear evidence of cats threatening to harm the overall population level of any particular species… Indeed, cats have been kept as pets for many years and hundreds of generations of birds breeding in suburban and rural areas have had to contend with their predatory intentions.” [4]

The German zoologist Paul Leyhausen (1916–1998), who spent the bulk of his career studying the behavior of cats, found that cats, frustrated by the difficulties of catching them, “may soon give up hunting birds.” [5]

“During years in the field,” wrote Leyhausen, “I have observed countless times how cats have caught a mouse or a rat and just as often how they have stalked a bird. But I never saw them catch a healthy songbird that was capable of flying. Certainly it does happen, but, as I have said, seldom. I should feel sorry for the average domestic cat that had to live solely on catching birds.” [5]

“Cats kill an estimated 480 million birds per year (assuming eight birds killed per feral cat per year).”

Fitzgerald and Turner (whose work is not referenced in the report) argue that “we do not have enough information yet to attempt to estimate on average how many birds a cat kills each year.” [3] Though, of course, many studies have tried to do exactly that—few, it should be said, involve feral cats.

“Estimates from Wisconsin indicate that between 500,000 and 8 million birds are killed by rural cats each year in that state…”

How anybody could misquote the numbers from the Wisconsin Study—easily the most widely circulated work on the subject—is a mystery. (On the other hand, the figures were, as Stanley Temple has said, “not actual data” [6] in the first place, so I suppose that does allow for some rather liberal interpretation.)

How important is it that the prey of feral cats is native, versus non-native? That’s a point of some debate—but not in this case. See, what Liberg actually wrote was this: “Most cats (80-85%) were house-based and obtained from 15 to 90% of their food from natural prey, depending on abundance and availability of the latter.” [7, emphasis mine] He was merely drawing the distinction between food provided by humans and any prey that cats might eat as food.

“In California, 67 percent of rodents, 95 percent of birds, and 100 percent of lizards brought home by cats were native species, and native birds were twice as likely to be seen in areas without cats.”

What looks to be truly damning evidence loses much of its impact when it’s seen in context. The reference to Crooks and Soulé’s 1999 paper, for example, omitted the sample size involved: “Identification of 68 prey items returned by cats bordering the fragments indicated that 67% of 26 rodents, 95% of 21 birds and 100% of 11 lizards were native species.” [8] It’s important to note, too, that these researchers asked residents to recall what kind of prey their cats returned—no prey items were collected—thereby raising questions about the accuracy of species attribution.

Furthermore, the cats involved with Crooks and Soulé’s study were all pet cats. How their habits compare with those of feral cats is an open question. Merritt Clifton of Animal People, an independent newspaper dedicated to animal protection issues, suggests, “feral cats appear to hunt no more, and perhaps less, than free-roaming pet cats. This is because, like other wild predators, they hunt not for sport but for food, and hunting more prey than they can eat is a pointless waste of energy.”

The second portion of the quote refers to Cole Hawkins’ PhD dissertation. Hawkins’ research methods and analysis are so problematic that the suggestion of a causal relationship between the presence of cats and the absence of birds (native or otherwise) is highly inappropriate (indeed, Hawkins scarcely investigates predation at all).

Among the key issues: Hawkins had no idea what the “cat” area of his study site was like before the cats were there; he merely assumes it was identical to the “no cat” area in terms of its fauna (though the two landscapes are actually quite different). It’s also interesting to note Hawkins’ emphasis on “the preference of ground feeding birds for the no-cat treatment” while downplaying the fact that five of the nine ground-feeding species included in the study showed no preference for either area. (For a more comprehensive analysis, please see my previous post on the subject.)

“…cats are the most important species in the life cycle of the parasite responsible for toxoplasmosis, and in 3 separate studies, most feral cats (62 percent to 80 percent) tested positive for toxoplasmosis.”

While cats are the “definitive host,” it’s important to note that “wild game can be a source of T. gondii infection in humans, cats, and other carnivores. Serologic data show that a significant number of feral pigs, bears, and cervids are exposed to T. gondii.” [9]

“Humans,” write Elmore et al., “usually become infected through ingestion of oocyst-contaminated soil and water, tissue cysts in undercooked meat, or congenitally. Because of their fastidious nature, the passing of non-infective oocysts, and the short duration of oocyst shedding, direct contact with cats is not thought to be a primary risk for human infection.” [10]

Toxoplasma gondii has been linked to the illness and death of marine life, primarily sea otters [11], prompting investigation into the possible role of free-roaming (both owned and feral) cats. [12, 13] It’s generally thought that oocysts (the mature, infective form of the parasite) are transferred from soil contaminated with infected feces to coastal waterways by way of freshwater run-off. [13]

However, a 2005 study found that 36 of 50 sea otters from coastal California were infected with the Type X strain of T. gondii [14], a type linked to wild felids (mountain lions and a bobcat, in this case), but not to domestic cats. [13] A recently published study from Germany seems to corroborate these findings. Herrmann et al. analyzed 18,259 fecal samples (all from pet cats) for T. gondii and found no Type X strain. (It’s interesting to note, too, that only 0.25% of the samples tested positive for T. gondii).[15]

[NOTE: Please see follow-up post for additional information about cats and T. gondii.]

“Predation by cats on birds has an economic impact of more than $17 billion dollars [sic] per year in the U.S. The estimated cost per bird is $30, based on literature citing that bird watchers spend $0.40 per bird observed, hunters spend $216 per bird shot, and bird rearers spend $800 per bird released.”

According to this bizarre form of accounting, hunters value an individual bird more than 500 times as much as a birdwatcher does—suggesting, it seems, that dead birds are far more valuable than live birds. This is the kind of estimate that can be developed only through university (or perhaps government) research efforts.

Public Indecency
“Stephen Vantassel, a wildlife damage project coordinator who worked on the study, said researchers were aware that some people would be ‘very offended that we offered any type of lethal control method.’ But he said the report was written for public consumption and wasn’t submitted to any science journals for publication.” [1]

For the record, Dr. Vantassel, I’m more offended by the way you’ve allowed such sloppy, grossly irresponsible work to pass for “research.” And the idea that such an undertaking is somehow acceptable because it’s meant for a mass audience is simply absurd!

Naturally, the American Bird Conservancy (ABC) embraced the report immediately, “with one official calling it ‘a must read for any community or government official thinking about what to do about feral cats.’” [1]

“‘Not surprisingly, the report validates everything American Bird Conservancy has been saying about the feral cat issue for many years—namely, TNR doesn’t work in controlling feral cat populations,’ Darin Schroeder, vice president of the Conservation Advocacy for American Bird Conservancy, said Tuesday.”

But validation requires far more than this report provides—beginning with a real interest in scientific inquiry and some basic critical thinking skills. And while we’re at it, a refresher in ethics wouldn’t hurt, either.

Results from the American Pet Products Association’s 2009­­–2010 National Pet Owners Survey suggest that cats in this country are spending more time indoors than ever before. Although the proportion of owners keeping their cats inside at night has remained relatively steady since 1998 (at approximately 66%), their has been a 14% increase in daytime confinement (from 56% to 64%) over the same period. [1]

It must be noted that owners were asked where they usually kept their cat(s), thereby raising some doubts about the accuracy of their responses. (There are actually two issues here: first is the level of truthfulness—did owners, intentionally or not, provide accurate information? But there is also the obvious ambiguity surrounding the term usually.) Nevertheless, these results correspond reasonably well with those of two earlier surveys: one commissioned by the American Bird Conservancy (ABC) in 1997, [2] the other conducted by Clancy et al. in 2001 [3] (the only other surveys I’ve found that investigated this issue specifically).

The ABC’s study (in which 250 cat owners participated in a telephone survey) indicated that “35% keep their cats indoors all of the time,” while “31% keep them indoors mostly with some outside access.” [2]

The 2001 survey included 168 cat owners, each of whom was part of the Feline Health Study, conducted at the Foster Hospital for Small Animals, Cummings School of Veterinary Medicine, Tufts University. Sixty percent of these cats were “strictly indoor cats,” while 40% “had some level of outdoor access.” [3] Probing further, Clancy et al. discovered that nearly half of the cats with outdoor access were outside for two or fewer hours a day. And 29% of them were outdoors for less than an hour each day. [3]

Considering the differences in sampling (most notably the fact that participants in the 2001 survey were all clients of a veterinary hospital, whereas APPA survey results for 2000 indicate that 27% of cat owners did not visit the vet in the previous 12 months), and the inherent uncertainty surrounding the terms mostly, usually, and some, the results of these three surveys are remarkably similar.

Counting Cats
Such findings are critical for developing accurate estimates of the number of birds killed by cats (assuming a reasonable level of accuracy is achievable, given the complexity of the issue). Simply put, cats that don’t go outside can’t kill birds.

Recognizing this, some researchers have inflated their figures for cats allowed outdoors. [4–6]

Dauphiné and Cooper, [6] for instance, cite the APPA’s 2007–2008 survey when referring to the number of owned cats in the U.S., but either ignored or overlooked its findings about confinement: 63% of owners reported that they kept their cat(s) indoors during the day, 70% during the night. (It’s also possible that the authors consulted only the APPA’s online summary, which probably didn’t include this information.)

By contrast, Dauphiné and Cooper claim that 65% of pet cats “are free-ranging outdoor cats for at least some portion of the day,” [6] citing not the APPA survey, but Linda Winter’s 2004 paper, “Trap-neuter-release programs: the reality and the impacts” (which can be downloaded here). Indeed, Winter, the former director of the ABC’s Cats Indoors! campaign, had suggested as much—misrepresenting the findings of a study commissioned by her own organization:

“A 1997 nationwide random telephone survey indicated that 66% of cat owners let their cats outdoors some or all of the time.” [7]

Counting Birds
Of course, such estimates do not necessarily relate directly to population impacts. The predation may be largely compensatory, for example; and there are source-sink dynamics to be considered as well.

Nevertheless, researchers persist—more often, it seems, in pursuit of staggering, media-friendly figures than a better understanding of what’s actually going on (e.g., Dauphiné and Cooper’s bumper-sticker-worthy “one billion birds”). As a result, the scientific literature is plagued with some rather spectacular failures where predation numbers are concerned (e.g., The Wisconsin Study, Christopher Lepczyk’s dissertation, Carol Fiore’s thesis, etc.).

* * *

The surprising level of agreement among the three “outdoor access” studies provides researchers a rare opportunity to agree among themselves. Which, in turn, could move us closer to an honest debate of the larger issues—arguing about which action is most appropriate, for instance, rather than about whose numbers are most valid.

Despite how results of these surveys have been—as recently as last year—overlooked, ignored, and misrepresented, I remain cautiously optimistic. As Patronek has suggested, “predation of songbirds tends to be noticed because it takes place during the day.” [8] It’s time predation research received the same kind of visibility. Sunlight, after all, is said to be the best of disinfectants.

6. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2009. p. 205–219.

7. Winter, L., “Trap-neuter-release programs: the reality and the impacts.”Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1369-1376.

Listening to NPR’s On the Media this weekend, I was struck by a story (first broadcast in 2006) about how certain “sticky” numbers—however dubious—find their way into the media landscape and beyond, as On the Media co-host Brooke Gladstone noted:

“Four years ago, we delved into the mysterious number, said to be 50,000, of child predators online at any given time. It was cited by the NBC Dateline program “To Catch a Predator” and also by then Attorney General Alberto Gonzales.

But spokespersons for the FBI, the National Center for Missing and Exploited Children, and the Crimes against Children Research Center said it was not based on any research they were aware of. The A.G.’s office at the time, well, they said it came from Dateline.”

“An interesting phenomenon of these numbers is that they’ll often be cited to an agency or some government body, and then a study will pick it up, and then the press will repeat it from that study. And then once it appears in the press, public officials will repeat it again, and now it’s become an official number.”

All of which sounds very familiar—Bialik could easily be describing the “official numbers” put out by so many TNR opponents. Among those that have gained the most currency are the predation estimates from the Wisconsin Study, the American Bird Conservancy’s figure for the proportion of birds in the diets of free-roaming cats, and Dauphiné and Cooper’s estimate of free-roaming cats in the U.S.

“The media has had a field day with this since we started. Those figures were from our proposal. They aren’t actual data; that was just our projection to show how bad it might be.” [3]

It’s true: the media has had a field day. Among the major newspapers to cite the Wisconsin Study are the Wall Street Journal [4], the New York Times [5], and the Los Angeles Times [6]. However, as I’ve described previously, it’s been the wildlife conservationists and bird advocates who’ve really had a field day with the Wisconsin Study:

The American Bird Conservancy (ABC) refers to the study, in its brochure Domestic Cat Predation on Birds and Other Wildlife. And the ABC goes one step further, pointing out that Coleman and Temple’s estimate was for rural cats, and that “suburban and urban cats add to that toll.” [7]

A 2009 article in Audubon Magazine suggests “cats were annually knocking off somewhere in the neighborhood of 8 million birds just in rural Wisconsin.” [9] To the magazine’s credit, they used Coleman and Temple’s low estimate—but none of the numbers from the Wisconsin Study are scientifically sound.

Birds Represent 20–30% of the Diet of Free-roaming Cats
According to an ABC report (downloadable from their website), “extensive studies of the feeding habits of domestic, free-roaming cats… show that approximately… 20 to 30 percent [of their diet] are birds.”

This, apparently, is the same report that Ellen Perry Berkeley debunked in her book, TNR Past Present and Future: A history of the trap-neuter-return movement, noting that the ABC’s 20–30% figure was not based on “extensive studies” at all. [10] In fact, just three sources were used: the now-classic “English Village” study by Churcher and Lawton [11], the Wisconsin Study (described above), and Mike Fitzgerald’s contribution to “The Domestic Cat: The Biology of Its Behaviour.” [12]

This gets a little complicated, so bear with me.

When Churcher and Lawton reported, “overall, birds comprised 35% of the total catch,” [11] they were referring to prey tallies recorded by study participants—not to the overall diets of the cats involved. Figures obtained through similar methods for the Wisconsin Study were 20–23%, [1, 13, 14] which the authors suggest—citing Fitzgerald’s comprehensive review of predation and dietary studies—are in line with other work:

“Extensive studies of the feeding habits of free-ranging domestic cats over 50 years and four continents [12] indicate that small mammals make up approximately 70% of these cats’ prey while birds make up about 20%.” [14]

But they’re comparing apples and oranges. Both the English Village and Wisconsin Studies report the percentage of birds returned as a portion of the “total catch,” whereas Fitzgerald reports percentage by frequency (i.e., the occurrence of birds in the stomach contents or scats of free-roaming cats), a point apparently lost on Coleman and Craven. The 21% figure [12] they refer to, then, is simply not comparable to their own (or that of the English Village study, a fact Churcher and Lawton acknowledge in their paper). As Berkeley notes, “this would put birds, as a portion of the diet of cats, at roughly 7 to 10.5 percent—nowhere near the ‘20 to 30 percent’ figures unleashed on the unscientific public by ABC!”

To put all of this into more familiar terms, it’s a bit like saying that coffee makes up 20–30% of the American diet versus saying that 20–30% of Americans drink coffee each day.

“…it has been estimated that birds represent 20–30% of the prey of feral and free-ranging domestic cats.”

Estimates of Free-roaming Cats
In January, Steve Holmer, the ABC’s Senior Policy Advisor, told the Los Angeles Times, “The latest estimates are that there are about . . . 160 million feral cats [nationwide].” Sounds like an awful lot of cats—nearly one for every two humans in the country. So where does this figure come from?

The source is a paper by Nico Dauphiné and Robert Cooper (which can be downloaded via the ABC website), presented at the Fourth International Partners in Flight conference. In it, Dauphiné and Cooper use some remarkably creative accounting, beginning with an unsubstantiated estimate of unowned cats, to which they add an inflated number of owned cats that spend time outdoors. In the end, they conclude that there are “117–157 million free-ranging cats in the United States.” [15] (For a more thorough explanation, see my previous post on the subject.)

Estimating the number of free-roaming cats wasn’t even the point of their paper. As the title—“Impacts of Free-ranging Domestic Cats (Felis catus) On Birds In the United States: A Review of Recent Research with Conservation and Management Recommendations”—suggests, the primary purpose was to describe the cats’ impact on birds. The authors’ exaggerated figure was merely a convenient route to their estimate of birds killed annually by cats: “a minimum of one billion birds” [15] (which, it should be clear, has the potential to become a very sticky number).

Holmer goes a step further, using only the upper limit of the range published by Dauphiné and Cooper, and making the subtle—but important—shift from free-ranging to feral cats.

When I asked him about this, he explained that those figures were “based on an earlier version of Nico’s latest paper and are now being updated in our materials.” I don’t know that any such changes were made; and in any event, the bogus estimate has already been published in the L.A. Times—as if it were true.

* * *

TNR opponents will often point to the vast collection of research studies, government reports, news accounts, and the like, that support their assertions. Drill down a bit into that collection, though, and they all start to look alike: the same familiar sources, the same flawed studies—and the same bogus figures. These figures have become the kind of “official numbers” Bialik refers to: quantitative poseurs owing their popularity to tireless—and irresponsible—repetition more than anything else.

11. Churcher, P.B. and Lawton, J.H., “Predation by domestic cats in an English village.”Journal of Zoology. 1987. 212(3): p. 439-455.

12. Fitzgerald, B.M., Diet of domestic cats and their impact on prey populations, in The Domestic cat: The biology of its behaviour, D.C. Turner and P.P.G. Bateson, Editors. 1988, Cambridge University Press: Cambridge; New York. p. 123–147.

15. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2009. p. 205–219.

“…it may be that conservation biologists and wildlife ecologists believe the issue of feral cats has already been studied enough and that the work speaks for itself, suggesting that no further research is needed.”

In fact, “the work”—taken as a whole—is neither as rigorous nor as conclusive as Lepczyk et al. suggest. And far too much of it is plagued by exaggeration, misrepresentations, errors, and obvious bias. In Part 3 of this series, I discussed the distinction between compensatory and additive predation. Here, I’ll focus on how feral cat/TNR researchers often misuse averages to characterize skewed distributions, and how that error overestimates the impact of free-roaming cats on wildlife.

Something’s Askew
When a data set is skewed, it is inappropriate to use the mean, or average, as a measure of central tendency. The mean should be used only when the data set can be considered normal—the familiar bell curve. As Woods et al put it:

“the simple average number of animals brought home is not a useful measure of central tendency because of the skewed frequency distribution of the numbers of prey items brought home…” [2]

Studies of cat predation routinely reveal a positively skewed distribution; a few cats are responsible for many kills, while many of the cats kill few, if any, prey. So when researchers use the mean to calculate the total number of prey killed by cats in a particular area, they overestimate the cats’ impact.

How common is this? Very [see, for example, 3-9]. Of the many cat predation studies I’ve read, only a few [2, 10, 11] properly account for the skewed nature of this distribution. And others [12-17] often take these inflated figures at face value—as evidence of the impact cats have on wildlife. Published repeatedly, the erroneous estimates take on an undeserved legitimacy.

The proper method for handling skewed distributions involves data transformations, the details of which I won’t go into here. The important point is this: in the case of a positively skewed distribution, the back-transformed mean will always be less than the simple mean of the same data set.

Big Deal
Depending on the particular distribution, the difference between the simple mean and the back-transformed mean can be considerable. Let’s use the 2003 study by Woods et al. [2] to illustrate. In the case of mammals killed and returned home by pet cats, the back-transformed mean was 28.3% less than the simple mean. Or, put another way, the simple mean would have overestimated the number of mammals killed by 39.5%. Similarly, when all prey items were totaled (as depicted in the illustration above), the simple mean would have overestimated the total number off all prey (mammals, birds, herpetofauna, and “others”) by 46.9%.

On the other hand, the figures for birds appear to break the rule mentioned above. In this case, the back-transformed mean (4.1) is actually a bit higher than the simple mean (4.0). How can this be? In order to log-transform the data set, Woods et al. had to first eliminate all the instances where cats returned home no prey—you can’t take the logarithm of 0. So, they were actually working with two data sets. Now, the second data set—which includes only those cats that returned at least one prey item—is also highly positively skewed. As a point of reference, its simple mean was approximately 5.6 birds/cat, which, compared to the back-transformed mean, is an overestimation of 37.5%.

By now, it should be apparent that log-transformed means have another important advantage over simple means: because you have to eliminate those zeros from the data set, you are forced to focus only on the cats that returned prey home—which, of course, is the whole point of such studies! And in the case of this study, Woods et al. found that 20–30% of cats brought home either no birds or no mammals. And 8.6% of the cats brought home no prey at all over the course of the study.

Transforming a data set (and then back-transforming its mean) is simpler than it sounds, but Barratt offers a useful alternative, rule-of-thumb method (one echoed by Fitzgerald and Turner [18]):

“…median numbers of prey estimated or observed to be caught per year are approximately half the mean values, and are a better representation of the average predation by house cats based on these data.” [10]

So, whereas Dauphiné and Cooper (and others) suggest increasing such estimates by factors of two and three (“predation rates measured through prey returns may represent one half to less than one third of what pet cats actually kill…” [14]), they should, in fact, be reducing them by half.

Cat Ownership
There are other instances in which simple averages are used to describe similarly skewed distributions—with similar results. That is, they overestimate a particular characteristic—and not in the cats’ favor.

Cat ownership, for example, is not a normal distribution. Many people own one or two cats; a few people own many cats. This is precisely what Lepczyk et al. found in their 2003 study:

“The total number of free-ranging cats across all landscapes was 656, ranging from 1 to 30 per landowner…” [6]

In fact, about 113 (I’m estimating from the histogram printed in the report) of those landowners owned just one cat apiece. About 70 of them owned two cats. Only one—maybe two—owned 30 cats. And yet, Lepczyk et al. calculate an average of 2.59 cats/landowner (i.e., 656 cats/253 landowners who allow their cats outdoors), thereby substantially overestimating cat ownership—and, in turn, predation rates (which calculations are based upon the average number of cats/landowner).

Lepczyk et al. are not the only ones to make this mistake; several other researchers have done the same. [4, 5, 7-9]

Outdoor Access
The amount of time cats spend outdoors is also highly positively skewed, as is apparent from the 2003 survey conducted by Clancy, Moore, and Bertone. [19] Their work showed that nearly half of the cats with outdoor access were outside for two or fewer hours a day. And 29% were outdoors for less than an hour each day.

Among those researchers to overlook the skewed nature of this distribution are Kays and DeWan, who calculate an average of 8.35 hours/day. This greatly overestimates potential predation, and leads them to conclude—erroneously—that the actual number of prey killed by cats was “3.3 times greater than the rate estimated from prey brought home,” [9] as was discussed previously.

Compound Errors
Clearly, these errors are substantial—in some cases, doubling the apparent impact of cats on wildlife. Of course the errors are even more significant when one inflated figure is multiplied by another—as when Lepczyk et al. [6] multiply the average number of prey items returned by the average number of outdoor cats per owner. The resulting predation figures may well be four times greater than they should be! (Actually, there are additional problems with the authors’ predation estimates, which I’ll address in a future post).

* * *

The fact that such a fundamental mistake—one a student couldn’t get away with in a basic statistics course—is made so often is shocking. The fact that such errors slip past journal reviewers is inexcusable.

14. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2010. p. 205–219

“…it may be that conservation biologists and wildlife ecologists believe the issue of feral cats has already been studied enough and that the work speaks for itself, suggesting that no further research is needed.”

In fact, “the work”—taken as a whole—is neither as rigorous nor as conclusive as Lepczyk et al. suggest. And far too much of it is plagued by exaggeration, misrepresentations, errors, and obvious bias. In a previous post, I presented examples of researchers drawing big conclusions from small sample sizes. Here, I’ll discuss the important distinction between compensatory and additive predation—a point too often left out of the feral cat/TNR discussion.

Sins of Omission
Focusing on the number of prey injured or killed by cats, without also recognizing that there are different types of predation, implies that each and every bird, mammal, reptile, etc. is destined to be part of its species’ breeding population. Of course, that’s not at all how things work out in the natural world—with or without predation by cats.

And yet, numerous studies [2-10], reviews [11], and other published papers [12-14] fail to acknowledge the critical difference between compensatory predation (in which prey would have died even in the absence of a particular predator, due to illness, starvation, other predators, etc.) and additive predation (in which healthy prey are killed). It’s the difference between, as Beckerman et al. put it, the “doomed surplus hypothesis” and the “hapless survivor hypothesis.” [15]

This is a critical point when it comes to connecting predation rates (from cats or any other predator) to population impacts. The more additive the predation, the greater the potential impact on population numbers. Purely compensatory predation, on the other hand, is less likely to affect overall populations. Of course, the connection is seldom so simple and direct, and a number of factors (e.g., habitat area and type, base population numbers, etc.) influence the ultimate outcome—making it quite difficult to tease out specific causal relationships. Nevertheless, if we want to better understand the impact of free-roaming cats on wildlife, we cannot ignore the distinction between—and inherent implications of—these two types of predation.

Honorable Mentions
Although Churcher and Lawton failed to mention the distinction between compensatory and additive predation in their now-classic “English village” study [4], Churcher later suggested that their findings were largely in the compensatory category: “If the cats weren’t there, something else would be killing the sparrows or otherwise preventing them from breeding.” [16]

Woods et al. don’t address the topic directly, but warn against drawing direct connections between predation numbers and potential effects on population dynamics:

“Our estimates of the total numbers of animals brought home by cats throughout Britain should be treated with requisite caution and these figures do not equate to an assessment of the impact of cats on wildlife populations.” [3]

Unfortunately, other researchers have used this study to make exactly that connection. In “Critical Assessment,” for example, Longcore et al. cite Woods et al. (along with Lepczyk et al. 2003, the subject of a future post) when they write, “evidence indicates that cats can play an important role in fluctuations of bird populations.” [11]

Under-Compensating?
In their 2008 study, Baker et al. found that “birds killed by cats in this study had significantly lower fat and pectoral muscle mass scores than those killed by collisions,” [17] suggesting that they may have been among the “doomed surplus” portion of the population. Similar results were reported eight years earlier by Møller and Erritzøe, who found that “small passerine birds falling prey to cats had spleens that were significantly smaller than those of conspecifics that died for other reasons,” concluding ultimately that the birds killed by cats “often have a poor health status.” [18]

But Baker et al. express caution about their findings:

“…the distinction between compensatory and additive mortality does… become increasingly redundant as the number of birds killed in a given area increases: where large numbers of prey are killed, predators would probably be killing a combination of individuals with poor and good long-term survival chances.”

Whatever their concerns, it must be noted that Baker et al. inflated their predation numbers by a factor of 3.3 on the basis of Kays and DeWan’s dubious conclusions [9] (which I discussed in some detail previously). Doing so raises considerable doubts about any level of “redundancy,” as well the authors’ suggestion that cat predation in the area might be “creating a dispersal sink for more productive neighboring areas.” [19] (Such “sinks” can occur when predation outstrips local prey populations, requiring that prey be “recruited” from surrounding areas.)

Implications
Given all the work that’s been done on cat predation, one might expect the subject of compensatory predation to be addressed more fully and more often. By omitting this important issue from the feral cat/TNR discussion, researchers portray a situation both simpler and harsher (in terms of what it implies about the impact of free-roaming cats) than reality suggests. Whether or not such omissions are intentional, I cannot say. I do, however, find it curious—what’s included compared to what’s left out, and by whom.

12. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2010. p. 205–219

“…it may be that conservation biologists and wildlife ecologists believe the issue of feral cats has already been studied enough and that the work speaks for itself, suggesting that no further research is needed.”

In fact, “the work”—taken as a whole—is neither as rigorous nor as conclusive as Lepczyk et al. suggest. And far too much of it is plagued by exaggerations, misrepresentations, errors, and obvious bias. For the next few posts, I’m going to present a sampling of its more serious flaws, beginning with how some researchers “reinterpret” work of others to suit their own purposes.

Tell It Like It Is
Studies of cat predation frequently cite the work of William G. George, who, in 1974, published a paper documenting his meticulous observations of the hunting behavior of three cats on his southern Illinois farm. “The results,” wrote George, “established a basis for examining the possibility that cat predation may result in depleted winter populations of microtine rodents and other prey of Red-tailed Hawks, Marsh Hawks, and American Kestrels.” [2]

Thirty years later, David A. Jessup interpreted things rather differently, giving George’s work an additional—and unwarranted—degree of certainty. Gone are the doubts that George expressed—first, regarding the impact of cat predation on rodent and other prey populations; second, regarding the relationship between these populations and the raptors that feed on them. For Jessup—who offers no additional evidence—it’s all very straightforward: “Feral cats also indirectly kill native predators by removing their food base.” [3]

More recently, Guttilla and Stapp seem to prefer Jessup’s take: “Human-subsidized cats… can spill over into less densely populated wildland areas where they reduce prey for native predators (George 1974).” [4]

If any additional work has been done on the subject (surely there are more cats in the area these days; how are the voles and raptors faring?), it seems to have gone unnoticed. Instead, Jessup, Guttilla, and Stapp (and others, too, no doubt) have simply rewritten George’s conclusion to suit their own purposes. Perhaps their version makes for a better story, but it’s rather poor science.

At the risk of drawing too many parallels between the two papers, I think the same can be said for Coleman and Temple’s infamous “Wisconsin Study.” (On the other hand, it does serve a useful purpose as a red flag.) Actually, as Goldstein et al. point out, Coleman and Temple’s paper was never peer-reviewed (not necessarily a deal-breaker in my book, but such publications do warrant additional scrutiny), but achieved its mythical status by being cited ad nauseam in peer-reviewed journals, as well as the mainstream media.

Does anybody actually believe the numbers suggested by Coleman and Temple? Stanley Temple (one of the co-authors of the recent anti-feral cat/TNR comment in Conservation Biology) himself admitted their published figures “aren’t actual data; that was just our projection to show how bad it might be.” [5]

I don’t think Longcore et al. [6] or the editors at Conservation Biology put much stock in the Wisconsin Study—so why continue to publish “projections” that have been so thoroughly discredited? Because doing so strengthens their case, at least among those who don’t know any better—especially people outside the scientific community, including many journalists, policy makers, judges, and the general public.

In their recent comment, Lepczyk et al. suggest that conservation biologists and wildlife ecologists “look to the evolutionary biology community” [1] for an example of how to influence policy:

“When local policies or regulations are put forth that promote the teaching of creationism or intelligent design, the evolutionary biologists have responded in force from across the nation and world.” [1]

Let’s set aside for the moment all the baggage associated with their analogy. My question is this: Is the evolutionary biology community still publishing bogus “projections” from 13 years ago? I doubt it.

Check Your Premises
In their recent paper (available for download via the American Bird Conservancy (ABC) website), Dauphiné and Cooper arrive at their absurd figure of “117–157 million free-ranging cats in the United States,” [7] in part, by way of Jessup’s “estimated 60 to 100 million feral and abandoned cats in the United States.” [3]

So where does Jessup’s figure come from? We have no idea—there’s no citation. And Jessup is no authority on the subject—having conducted no studies or reviews of studies that quantify the feral cat population. What’s more, his “estimation” is among the highest figures published. Yet this is the shaky foundation upon which Dauphiné and Cooper attempt to build their subsequent argument.

The authors then add to the (dubious) number of feral cats the proportion of pet cats allowed outdoors. They refer to a 2004 paper by Linda Winter, director of ABC’s Cats Indoors! campaign, in which it was reported, “A 1997 nationwide random telephone survey indicated that 66% of cat owners let their cats outdoors some or all of the time.” [8]

That’s an interesting way to put it—Winter makes it sound like two-thirds of pet cats are essentially outdoor cats. But the survey—commissioned by ABC!—actually indicates that “35% keep their cats indoors all of the time” and “31% keep them indoors mostly with some outside access.” [9] The difference in wording is subtle, and hampered by imprecision—it all comes down to the meaning of some.

Winter’s 2004 paper implies that there are twice as many outdoor pet cats as was indicated in the original survey—an interpretation Dauphiné and Cooper seem to embrace. Had they looked further—and to a less biased source—they might have been able to get a better handle on the degree of outdoor access. For example: a 2003 survey conducted by Clancy, Moore, and Bertone [10] revealing that nearly half of the cats with outdoor access were outside for two or fewer hours a day. And 29% were outdoors for less than an hour each day.

Do these “part-timers” have the same impact on wildlife as feral cats? Dauphiné and Cooper would have us believe they do.

[Note: For a closer look at the flaws in Dauphiné and Cooper’s paper, download “One Billion Birds,”by Laurie D. Goldstein.]

The lesson? Credible research begins with a solid foundation; a weak foundation—one plagued with unsubstantiated claims—on the other hand, leads to pseudoscience.

When All Else Fails, Look It Up
Though this would seem to be utterly obvious, it apparently bears repeating: Don’t cite work you haven’t actually read.

Isn’t this emphasized in all graduate (indeed, undergraduate, too) programs? What grad student isn’t, at one time or another, tempted to take the easy way out—ride the coattails of somebody else who’s (presumably) done the real work? In addition to the ethical implications, such shortcuts tend to invite more immediate troubles, too. Again, George’s work (described above) provides an excellent case study. Below are some examples of how his work has been referenced in the cat predation literature:

“It is very unlikely that cats bring home all of the prey that they capture. What proportion they bring home has been little studied. George (1974) on a farm in Illinois USA found that three house cats, all adequately fed, brought home about 50% of the prey that they killed.” [11]

“George found that about 50% of prey were indeed brought home, with the other 50% being eaten, scavenged by other animals or simply not found.” [12]

“These approximations are probably underestimates, assuming that cats do not bring back all the prey that they kill.” [13]

Trouble is, George never said these things; what he said was:

“… the cats never ate or deposited prey where caught but instead carried it into a ‘delivery area,’ consisting of the house and lawn. The exclusive use of this delivery area was verified in 18 to 70 mammal captures per cat, as witnessed between early 1967 and 1971.” [2]

In 2000, Fitzgerald and Turner pointed out the fact that George’s work was being misrepresented, noting that the erroneous 50% figure “has been reported widely, though it is unfounded.” [14] Nevertheless, the myth persists—even in 2010.

“In Illinois, George (1974) found that only about half of animals killed by cats were provided to their owners, and in upstate New York, Kays and DeWan (2004) found that observed cat predation rates were 3.3 times higher than predation rates measured through prey returns to owners. Thus, predation rates measured through prey returns may represent one half to less than one third of what pet cats actually kill…” [7]

As Dauphiné and Cooper demonstrate, the “reinterpreted” version of George’s work makes for a very convenient multiplier—suddenly,every kill reported is doubled (or tripled, if Kays and DeWan are to be believed—and they’re not, but that’s a topic for another post). Never mind the fact that it has no basis in actual fact.

Getting a copy of George’s study isn’t difficult, especially with the inter-library loan services available today. To reference it—to use George’s work so that your own appears more credible—without ever having actually read it, is simply inexcusable. But citing it blindly suggests more than laziness—it points to a certain coziness that has no place in scientific discourse. Too much Kool-Aid drinking, and not enough honest research.

* * *

Scientists can (and do) look at identical results and come to very different conclusions. But misinterpreting, misrepresenting, or dismissing the conclusions of others, is something else altogether. As the above examples (and there are many, many more!) illustrate, this happens far too often in the feral cat/TNR literature. And if we can’t believe what researchers are saying about the work of others, why would we believe what they say about their own work?

Next, I’ll focus on some of the major flaws in the feral cat/TNR literature—beginning with small sample sizes…

7. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2010. p. 205–219

8. Winter, L., “Trap-neuter-release programs: the reality and the impacts.”Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1369-1376.

Like so many others interested in blaming cats for declining bird populations, Longcore et al. refer to a 1996 article in Wisconsin Natural Resources magazine [1], in which the authors estimate that 8–219 million birds are killed annually by “free-ranging rural cats” in the state. More than any other work, the “Wisconsin Study” (which is actually a series of articles, the first being published in 1993 [2]) has been used as “evidence” against advocates for free-roaming cats in general, and TNR in particular.

In my previous post, I referred only briefly to Coleman and Temple’s work; in fact, careful scrutiny is in order. Among the study’s more notable flaws:

Its “estimate that 23 percent of [cats’] diet consists of birds” is well above the 7–10.5% figure suggested by Fitzgerald, [3] one of the world’s foremost experts on the subject (for a detailed account, see Ellen Perry Berkeley’s 2004 book, TNR Past present and future: A history of the trap-neuter-return movement [4]). In fact, Coleman and Temple cite Fitzgerald’s work, making the error all the more egregious.

Coleman and Temple assume that all cats hunt; in fact, it has been suggested that only 35–56% of cats are hunters. [5,6]

Their figures for cat density, too, have been challenged. [7]

For a more complete critique of the Wisconsin Study, download the 2003 report by Laurie D. Goldstein, Christine L. O’Keefe, and Heidi L. Bickel at Stray Pet Advocacy.

Now 14 years old, the Wisconsin Study has achieved mythical status—but not in a good way. I suppose it’s because the numbers are so impressive. Forget the fact that they’re essentially fictitious—they’re simply too tempting for people who see cats as the primary reason for declining bird populations. James Tantillo, a Lecturer in the Department of Natural Resources at Cornell University’s College of Agriculture and Life Sciences, is right on the money when he refers to Coleman and Temple’s estimate as an example of a “‘mutant statistic’ whose origins and genesis have been greatly lost to the people who cite it.” [8]

* * *

Among those who cite it are, of course, Longcore et al. But they failed to cite an important follow-up comment by one of the authors of the Wisconsin Study. In a 1994 interview, an “exasperated” Temple told The Sonoma County Independent:

The media has had a field day with this since we started. Those figures were from our proposal. They aren’t actual data; that was just our projection to show how bad it might be. [9]

More than the media, however, it’s been the wildlife conservationists and bird advocates who have had a field day with the Wisconsin Study. Here are just a few examples:

The American Bird Conservancy refers to the study in its brochure Domestic Cat Predation on Birds and Other Wildlife. But ABC goes one step further, pointing out that Coleman and Temple’s estimate was for rural cats, and that “suburban and urban cats add to that toll.” [10]

A recent article in Audubon Magazine suggests “cats were annually knocking off somewhere in the neighborhood of 8 million birds just in rural Wisconsin.” [11] To the magazine’s credit, they used Coleman and Temple’s low estimate (a surprise given the overall tone of the piece). Still, none of the numbers from the Wisconsin Study are scientifically sound (indeed, one can make a strong argument that none of the work constitutes actual research).

For Longcore et al. to cite the Wisconsin Study without even a mention of its numerous flaws, or the rather public admission by one of its authors that their estimates “aren’t actual data,” casts serious doubt on the entire paper. Either they didn’t know how flimsy Coleman and Temple’s work was, or they knew and ignored the facts. Neither approach makes for good science, of course.

* * *

Estimating the number of birds killed by cats is difficult enough; demonstrating that their predation is the cause of declining bird populations is an even greater challenge. Nevertheless, Longcore et al. suggest the evidence is both plentiful and compelling. I’ll lay out an argument to the contrary in my next post…

How many birds are killed by cats? It’s a fair question. And if Longcore et al. are to be believed, we actually have a pretty good handle on this issue:

Feral and free-roaming cats are efficient predators, and their abundance results in substantial annual mortality of wildlife. Churcher and Lawton (1987) concluded that cats were responsible for 30% of the mortality of House Sparrows (Passer domesticus) in an English village. May (1988) extrapolated their results to an estimated 100 million birds and small mammals killed per year in England. Although this extrapolation is often criticized for the limited geographic scope and number of cats studied, Woods et al. (2003) confirmed and refined this result with a larger sample size and geographic area that included England, Scotland, and Wales. From a survey of cat owners that documented prey returned by 696 cats, Woods et al. (2003) estimated that the 9 million cats in Britain kill at least 52–63 million mammals, 25–29 million birds, and 4–6 million reptiles each summer. In North America Coleman and Temple (1996) developed estimates of cat densities in Wisconsin and associated mortality of 8–217 million birds per year.

The relationship between cat predation and bird populations is highly complex, and our understanding quite limited—something Longcore et al. only hint at. It doesn’t help matters that results of small, isolated studies are often extrapolated from rural to urban environments, from one region to another, and so forth. In 1995, Churcher himself cautioned against making such leaps: “I’d be very wary about extrapolating our results even for the rest of Britain, let alone America,” he told Catnip, a newsletter published by the Cummings School of Veterinary Medicine at Tufts University.

Actually, Churcher went much further: “I don’t really go along with the idea of cats being a threat to wildlife. If the cats weren’t there, something else would be killing the sparrows or otherwise preventing them from breeding.” [1] Although Longcore et al. seem eager to cite Churcher and Lawton’s now-classic work as “evidence” of the damage cats can do, they make no mention of Churcher’s later comments (just one of many examples of their tendency to “cherry pick” from the literature only the bits and pieces that fit neatly into their argument).

But back to the number of birds killed by cats. Many of the studies on the subject—including those cited by Longcore et al.—are quite flawed. Among the numerous issues that call into question their estimates are assumptions regarding the number of cats that actually hunt, the number of cats allowed outdoors, the number of cats that live in a particular area, and so forth. And then, of course, there are the risks inherent in estimating population numbers and characteristics based on a small sample size.

(In fact, Woods et al. go to some lengths to emphasize the limitations of their study, conceding, for example, that they “may have focused on predatory cats.” [2] This is just one of many reasons the authors cite for requesting that their work be treated “with requisite caution”—a request apparently ignored by Longcore et al.)

By referring uncritically to such studies, Longcore et al. give far greater importance to this work than is warranted. Repeating—and therefore reinforcing—figures known to be erroneous and/or misleading is simply irresponsible.

The fact that the “English village” study and “Wisconsin Study” have been so thoroughly discredited (see, for example, the comments of Nathan Winograd, director of the No Kill Advocacy Center, and a report by Laurie D. Goldstein, Christine L. O’Keefe, and Heidi L. Bickel) raises some unsettling questions about their inclusion in a paper billed as a “critical assessment.” For example: Are the authors interested enough in rigorous scientific inquiry to look beyond “the usual suspects” in their assessment of the key issues?

One might also wonder: Given the important literature that Longcore et al. choose to overlook, ignore, or dismiss (to be addressed in detail in future posts), what is their motivation for writing the essay in the first place? Actually, this question was answered in January, two months after the paper’s publication, when L.A. Superior Court Judge Thomas McKnew decided in favor of an injunction against publicly supported TNR in Los Angeles (LASC BS115483). The Urban Wildlands Group (for which Longcore serves as Science Director, and Rich as Executive Officer) was the lead petitioner in the case.

If “Critical Assessment” is any indication, the case had much more to do with politics, PR, and marketing than with science.